There are several known machines for installing upholstery seat covers onto padded automobile seat frames. Such machines are commonly referred to as skinners by those skilled in the art. Some skinners operate vertically above an on-line conveyor which transports the seat through several stations, while other skinners are off-line or stand alone wherein seats are manually transported to the next assembly station.
One such prior skinner machine is disclosed in Fraiser, U.S. Pat. No. 4,385,427. Fraiser provides a carriage having a cluster of resilient cantilever arms that extend downward. In operation, an inside-out seat cover is slipped over the resilient arms. Then the carriage is translated towards a padded seat frame. The cantilever arms move along the outer of the padded seat frame causing the cover to be turned outside-out over the padded seat frame. A drawback with Fraiser is that it is unable to accommodate different sizes of seats. In particular, different models of vehicles have different sizes and shapes of seats which require different cover sizes. It is a disadvantage that this requires automotive manufacturers to have a different machine for each different size or shape of seat, and does not allow manufactures the flexibility to increase production of a certain size of seat that may be in short supply or inventory. This also can cause the skinner machine to become obsolete or require re-tooling if the particular seat size is discontinued by the automotive manufacturer. Another related problem is that the disclosed skinner machine of Fraiser can not be installed in an on-line seat assembly conveyor.
Another attempt at providing a skinner machine is disclosed in Mintz et al., U.S. Pat. No. 5,774,965. The skinner machine of Mintz includes self adjusting pneumatic actuators that drive four blades. At the beginning of the fitting cycle, the four blades are grouped close together so that a seat cover can be inserted inside-out on the blades. Then the blades are pneumatically actuated outward from one another to exert radially outward pressure on the seat cover. The seat cover counteracts the pneumatic force to stop the movement of the blades. Once the blades are stopped, a padded seat frame is driven towards the blades to skin the seat cover onto the padded seat frame outside-out. One very significant problem of Mintz is that the outward pressure on the seat covers causes an undesirable number of seat covers to pop or rip which results in wasted seat covers which in turn is very costly. Although Mintz et. al asserts to be adjustable for different sizes of seats by using pneumatic "self adjusting" actuators, the reality is that little if any adjustability is achieved and that a fixed sized seat cover and configuration is optimal for any given machine. Therefore, differently configured skinner machines are still necessary for different sizes of seat covers. Yet another problem of Mintz et. al is that the disclosed skinner can not be installed nor easily adapted to be installed in an on-line seat assembly conveyor. One last problem of Mintz is the quality of the skinned cover on the padded seat frame is low because the skinned cover on the seat usually has wrinkles and poor alignment which must be manually corrected, which is time-consuming and costly.